The Women's Estrogen for Stroke Trial (WEST) is a randomized, double- blind, placebo-controlled trial testing whether estrogen treatment, compared to placebo, reduces the risk of death or recurrent stroke in postmenopausal women with a transient ischemic attack or first non- disabling stroke. Patient accrual, which began in December 1993, was based on a sample size target of 652 women to detect a difference in endpoints of 10 percent (25 percent in placebo group and 15 percent in estrogen group). To date, the WEST has enrolled 561 patients and has been remarkably successful in maintaining high protocol adherence, patient participation, and clinical safety. Enrollment in WEST will be completed by May 31, 1998, before the start of the continuation period. Therefore, the principal aim for the competing renewal is to complete the WEST as originally proposed to ensure desired average length of patient follow-up of 3.5 years and to permit the necessary data management and analysis. The additional funded time is also needed to enable the trial investigators to arrange for appropriate termination of subject participation. A second aim for the competing renewal is to acquire new data about the clinical course and outcomes of TIA and non- disabling stroke in elderly women, and on the impact of estrogens generally in this special population. Indeed, few studies have had the opportunity to acquire detailed clinical, behavioral and cognitive data on the clinical course of stroke in a group of women this age who began their participation with high levels of functional independence. The goals of WEST are even more salient to the health of American women today than when they were proposed in 1992. Even now in 1997 no clinical trial data are available demonstrating estrogen's effect on vascular endpoints, including cerebrovascular, that would help postmenopausal patients and their physicians decide whether and when to use estrogens. Thus, the results of WEST promise to provide American women with urgently needed information that may help to reduce the risk of stroke and stroke-related mortality.